The invention relates to casters in general, and more particularly to improvements in casters of the type wherein the wheel frame is rotatable relative to its carrier about a first axis and the wheel is rotatable in the frame about a second axis which is inclined relative to the first axis. Still more particularly, the invention relates to improvements in casters wherein the frame can be blocked against rotation about the first axis and the wheel can be braked against rotation about the second axis.
It is already known to make the wheel and the frame of a caster from a suitable plastic material and to design the actuating mechanism for the braking and blocking devices in such a way that the mechanism employs a reciprocable plunger or pin which can be moved between a plurality of positions to thereby actuate or release the one and/or the other of these devices. An advantage of a caster wherein the frame and the wheel are made of a plastic material is that the selected plastic material can impart to such parts, and to the entire caster, an eye-pleasing appearance. By way of example, such casters can be used with advantage to support the legs of beds in hospitals, sanitaria, convalescent homes and similar establishments as well as in private residences. As a rule, a mobile bed is located in a building so that the wheels of its casters are caused to roll along a floor which is often provided with a covering of plastic material. This results in the development of a static charge when the plastic wheels are caused to roll along the plastic coating of the floor. The development of such charges is highly undesirable in many instances, for example, when the bed supports or is connected with one or more electrical diagnostic, treating and/or other implements, instruments and/or apparatus. The charges can affect the accuracy of such components and/or otherwise prevent them from operating in the prescribed manner. Prevention of propagation of such charges between the wheel and the carrier of the wheel frame is particularly difficult when the caster is provided with the aforediscussed braking and blocking devices which are necessary to prevent any movements of the wheel and/or to prevent any changes in the direction of movement of the wheel.